Topography of human transient and steady-state retinal responses elicited with dead leaves stimuli.

Abstract

Purpose : Checkerboards are being used to study the inner retinal responses in humans. However, due to their configuration and the recording challenges these responses pose, there is a gap in the literature on the topography of the transient (TR) and steady-state (SS) responses elicited by inner retina that this study aims to fill by using dead-leaves stimuli (DLS).

Methods : Twenty subjects (24.5±1.9 years) with BCVA 20/20 or better and no ocular pathologies participated in the study. Disks of increasing size (from 10^o to 50^o diameter in 10^o steps) and rings with an outer diameter of 50^o and an ablated center of increasing diameter (10^o to 40^o diameter in 10^o steps) were formed with ellipses of random orientation and size (between 0.5^o and 2^o) creating a DLS. The total number of DLS was nine with average contrast of 50% and average luminance equal to the background luminance (75 cd/m²). DLS were contrast reversing in time at either 1 rev/s or 7.5 rev/s, eliciting TR and SS responses, respectively. The DLS were presented on a 48” LG OLED monitor (120 Hz refresh rate). We recorded ERGs monocularly using a DTL electrode, with an undilated pupil. For analysis we used the amplitude and latency of the P1 and N2 components of the TR responses while the SS responses were Fourier-transformed to extract amplitude and phase of the 15 Hz harmonic.

Results : The P1 and N2 amplitude of the TR responses increases as a function of stimulus area (10^o to 50^o diameter) with a steeper increase in amplitude for the central 20^o, followed by a slower increase (2^nd degree polynomial fit, R²=0.993, p<0.02). As the center of the disks is ablated, P1 and N2 amplitudes decrease linearly (R²=0.945, p<0.01). The latency of the TR responses decreases slightly, but not significantly, as the stimulus area increases. The SS responses show increased amplitude as a function of stimulus area (2^nd degree polynomial fit, R²=0.965, p<0.01) and an exponential amplitude decrease as the central area is ablated (R²=0.996, p<0.01). The phase increases significantly between the 10^o and 20^o disks (p<0.001) and remains unchanged for bigger disks or when the central area is ablated.

Conclusions : It is possible to obtain TR and SS responses that offer retinal topographic information with the DLS. Vector addition models might be used for the SS responses to extract information of other stimulus configurations not used in the recordings.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.